摘要:

AbstractThe trophic structure of an ant community near Deniliquin, in south western New South Wales, was found to be complex. Individual species covered a range of trophic levels and, apart from a few specialized predators, most species showed a broad diet. A total of twenty‐seven species were placed in six different categories, according to food usage patterns:‐ specialist predators (2 spp.), generalist predators (1 sp.), predator‐scavengers (4 spp.), omnivore‐nectar collectors (10 spp.), omnivore‐seed collectors (5 spp.) and seed harvesters (5 spp.). Almost 50% of ant colonies were of the five seed‐harvester species and their food usage was examined more closely. They showed marked seasonal changes in composition of diet, corresponding closely to periods of seed production by different food plants. There were also differences in seed selection between species, and these were related to the size, phenology and probably chemical properties of the seed. Foraging behaviour by the various species showed differing adaptations to efficient utilization of a variable

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01269.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractColonization and abundance of mosquitoes and other insects were studied during four trials in man‐made ponds at Mildura, Victoria. In December and February, respectively,Culex australicusandCx annulirostriscolonized the ponds within 1 day of formation. Maximum larval densities were attained within 8 days and, thereafter, densities gradually declined. The ponds were also colonized initially by predatory Coleoptera and Hemiptera, then Odonata. In three of the four trials, a significant inverse relationship existed between mosquito and predator densities. From life tables compiled during one of these trials, a survival rate ofCx annulirostris, from egg hatch to eclosion, was estimated to be 11%. Predation was considered to be largely responsible for the low survival. The results are discussed in relation to control ofCx annulirostrisin temporary and permanent grassy pond

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01270.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractSixteen 1‐ha study plots covering five regeneration stages were simultaneously trapped five times over a 20‐month period to provide data on small mammal response to vegetation changes following fire. Areas regenerating after fires from 9 years to 1 month before the investigation were sampled in a uniform open forest on a coastal sand plain. Two types of understorey were recognized: one dominated by true forest shrubs with whichRattus fuscipes, Antechinus stuartiiandSminthopsis murinawere associated, and another dominated by heath elements where the addition ofPseudomys novaehollandiaeandMus musculusproduced a significantly more diverse small mammal community. The two communities exhibited different responses to post‐fire vegetation changes.Rattus fuscipeswas the most abundant species and showed a logistic growth in biomass. No resident populations were established in the first 3 years, but a rapid increase in biomass occurred from 3 to 5 years to plateau after 8 years. Regeneration age had the greatest effect onR. fuscipesbiomass mediated through the amount of accumulated leaf litter with additional variation being attributed to several vegetation structure variables and plant species diversity.A replacement sequence in time was observed for species reaching their maximum abundance(P. novaehollandiaeand/orM. musculus → S. murina → A. stuartii → R. fuscipes)and was interpreted as species occupying stages in the succession when their optimal habitat requirements were fulfilled. These results have important implications for the design of management policies using fire or fire regimes as tools for habitat maintenance or alteration. A mosaic of forest patches of adequate size covering the entire range of seral stages is necessary to meet the optimum requirements of all the ab

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01271.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractAn investigation ofEpiphyas postvittana(Walker), the light‐brown apple moth, was begun in 1961 to test the relevance of Nicholson's (1954) concepts of population dynamics, while gaining information on the distribution, abundance, and injuriousness of the species. This objective was redefined in the mid‐60s to comprise an empirical evaluation of the concept oflife system(Clarket al. 1967) as a frame of reference wherein to describe the numerical determination of species populations.It is concluded that: (1) in their elaboration as the life system concept, Nicholson's postulates provide an efficient schema for the study and explanation of numerical determination; (2) there are no limits to the possible extension and refinement of life system modelling as a means of explaining population events, although relatively crude, yet comprehensive, descriptions of functional processes would usually suffice for practical purposes; (3) information produced by life system studies is essential to the understanding and efficient management of pest situations; (4) because of the difficulty and cost of life system studies, ecologists should assemble increasingly refined and continuously up‐dated sets of reference models, or type cases, for use by entomologists to identify pest situations and prescribe curative action. Procedural implications are consi

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01272.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractDistinct O1and O2layers, representing annual litter fall, enabled the sequential loss of biomass and nutrients (phosphorus and nitrogen) to be reconstructed in undisturbed litter layers ofBanksia ornatain the Dark Island heathland, South Australia.Apart from an initial loss in biomass and nitrogen, the dry weight and nutrient content of the O1layer, exposed to the desiccating influence of the atmosphere, remained relatively constant until covered by the following year's leaf fall. Under the blanket of newly fallen leaves, biomass decomposition proceeded continuously through autumn, winter, spring, into the dry summer season. Even though the biomass of the decomposing leaf (O2) layer decreased continuously, its nutrient content remained relatively constant until the summer season was reached when total decomposition and nutrient loss occurred.During spring, fine rootlets invaded the decomposing litter layer (O2) and, together with decomposer fungi, bacteria and soil fauna, maintained the total nutrient content of the decomposing leaf at a constant level. By late spring‐early summer shoot growth of the dominant heath species was initiated, inducing the mobilization of the nutrients stored in the decomposing litter laye

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01273.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe movement of water and nutrients (N, P, K, Na, Mg, and Ca) throughEucalyptus regnansdominated catchments in the Maroondah catchment near Melbourne were determined. Nutrient fluxes in precipitation and streamflow are discussed and used to prepare simple precipitation input – stream flow output catchment budgets. These budgets are similar to those found elsewhere in Australia and overseas with the exception of nitrogen. This was probably due to errors in measurement and incomplete quantification of nitrogen fluxes. Catchment sodium budgets were used to estimate geological weathering rates by two different methods. Both methods yielded similar results. Data from two other studies in Victorian forested catchments yielded results similar to those obtained from Maroondah. It was concluded that the bedrock weathering rate at Maroondah was approximately 700 kg ha‐1year‐1which is very similar to that found elsewhere. Nutrient inputs from geological weathering were then estimated and possible errors disc

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01274.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA direct correlation was found between soil water stress and resistance ofE. occidentalisleaves to extreme temperatures. A distinct seasonal rhythm of heat and cold resistance of the leaves was recorded. Maximal tolerance was observed towards the end of the dry season, when the resistance value, that is, the temperature injuring 50% of the leaf area at Ilanot was –5.8°C for cold resistance and 51.0°C for heat resistance. The minimal tolerance to extreme temperatures was recorded in the middle of the rainy (winter) season.Irrigation of the trees during the summer reduced both heat and cold resista

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01275.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractGrowth of plant parts in different species inEucalyptus signatadominated forest in Queensland occurs at different times. Measurement of increments in root basal diameter combined with previously obtained regressions of root weight on root diameter allows separate estimation of the growth of woody root parts on a seasonal basis for the first time. The growth of lateral and of tap roots as well as of stems and leafy twigs, were separately measured on three tree species every 6 weeks for 2 years.Net primary productivity for the forest is estimated at 26 t ha‐1yr‐1, of which 66% is aboveground production, and 78% is contributed by a single species. This productivity rate is unexpectedly high, and may reflect a growth stimulus due to release of nutrients following a recent f

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01276.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe understorey vegetation of nine localities with different fire histories from open eucalypt forest near Melbourne, Victoria, was analysed by principal component analysis. Floristically, localities were quite similar; however, structural differences caused mainly by different burning regimes of recent years were more evident. An analysis of presence‐absence data displayed a marked discontinuity that was explainable in terms of the timing and intensity of a recent fire. Using unstandardized height data the pattern was related to inter‐ and intra‐locality differences in time since the last fires. An analysis of standardized height data demonstrated a connection between understorey structure and fire frequency. Despite apparent differences in the scatter diagrams obtained a statistical comparison of the analytical results indicated that, in many respects, the ordinations were s

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01277.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractAssociation‐analyses were made of montane grasslands (patanas) of Sri Lanka using higher plant and soil microfungal data. Stand classifications derived from higher plants and microfungi were remarkably parallel and were in complete agreement with the tentative division of patanas into five major types. The ecological distinctiveness of the five patanas was further evident from the phytosociological affinities of species indicated by classifications of higher plants and microfungi. Multivariate analyses of higher plants and fungi from the same ecosystem are regarded as alternative approaches which provide more information together than alon

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1981.tb01278.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY